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Isotopic and trace element geochemistry of lavas from the northern Mariana and southern volcano arcs

Thesis/Dissertation ·
OSTI ID:5299400
Samples from submarine volcanoes and islands were analyzed for concentrations of K, Rb, Sr, Ba, REE, {sup 87}Sr/{sup 86}Sr and some selected samples for {sup 143}Nd/{sup 144}Nd. These data show strong variations along the arc, being relatively depleted in the tholeiitic and low-K calc-alkaline volcanoes of the Volcano Arc (VA) and the Mariana Central Island Province (CIP). All of the Mariana Northern Seamount Province (NSP) and Volcano arc Iwo Jima (IJ) are enriched in LIL and LREE, particularly in the northern half, where the lavas have strong shoshonitic affinities. Chemical characteristics of these lavas suggest source- or melt-mixing, with the NSP shoshonites being derived from a LIL- and LREE-enriched OIB-like source or melt, while Mariana CIP and Volcano Arc melts are derived from a depleted MORB-like mangle that has been recharged with K, Rb, Sr and Ba by hydrous fluids. Neodymium and strontium isotopic data reveal {var epsilon}{sub Nd} values ranging from +2.4 to +9.5 and {sup 87}Sr/{sup 86}Sr from 0.70320 to 0.70405. Anomalous trends of {sup 87}Sr/{sup 86}Sr and Ba/La found in some S-NSP lavas suggest that the addition of a sedimentary component may be superimposed on the two component mixing. The lavas from the Mariana and Volcano arcs, therefore, are interpreted as resulting from mixing of at least three components. The bulk of the lavas derive from an OIB-like mantle source (or melt) mixing with various proportions of a metasomatized depleted mantle source (or melt). These hybrid sources may be contaminated with minor amounts of subducted sediment and fluxed by multistage-fractionated metasomatic fluid which is derived from subducted sediment and slab after the mixing of the first two components.
Research Organization:
Texas Univ., Dallas, TX (United States)
OSTI ID:
5299400
Country of Publication:
United States
Language:
English

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Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ALKALI METALS
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METALS
ALPHA DECAY RADIOISOTOPES
BARIUM
BETA DECAY RADIOISOTOPES
CHEMICAL COMPOSITION
CHEMISTRY
DEVELOPED COUNTRIES
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GEOCHEMISTRY
HOURS LIVING RADIOISOTOPES
INTERMEDIATE MASS NUCLEI
ISLANDS
ISOMERIC TRANSITION ISOTOPES
ISOTOPE RATIO
ISOTOPES
LAVA
MARIANA ISLANDS
METALS
NEODYMIUM 143
NEODYMIUM 144
NEODYMIUM ISOTOPES
NORTH AMERICA
NUCLEI
PACIFIC OCEAN
POTASSIUM
RADIOISOTOPES
RARE EARTH NUCLEI
RARE EARTHS
RUBIDIUM
SEAS
STABLE ISOTOPES
STRONTIUM
STRONTIUM 86
STRONTIUM 87
STRONTIUM ISOTOPES
SURFACE WATERS
TRUST TERRITORY OF THE PACIFIC ISLANDS
USA
VOLCANIC REGIONS
VOLCANOES
YEARS LIVING RADIOISOTOPES